Entropic multi-relaxation free-energy lattice Boltzmann model for two-phase flows

Aerothermochemistry and Combustion Systems Laboratory, Institute of Energy Technology, Department of Mechanical and Process Engineering, ETH Zurich - 8092 Zürich, Switzerland

Received: 8 December 2017
Accepted: 2 May 2018

Abstract

The entropic multi-relaxation lattice Boltzmann method is extended to two-phase systems following the free-energy approach. Gain in stability is achieved by incorporating the force term due to Korteweg's stress into the redefined entropic stabilizer, which allows simulation of higher Weber and Reynolds numbers with an efficient and explicit algorithm. Results for head-on droplet collisions and droplet impact on super-hydrophobic substrates are matching experimental data accurately. Furthermore, it is demonstrated that the entropic stabilization leads to smaller spurious currents without affecting the interface thickness. The present findings demonstrate the universality of the simple and explicit entropic lattice Boltzmann models and provide a viable and robust alternative to existing methods.